Small Form-factor Pluggable (SFP) modules are used in various telecommunication and data networking applications to interface between a printed circuit board in a network device and a network cable (which may be electrical or fiberoptic). Typically, the SFP receptacle is mounted on the printed circuit board with appropriate electrical connections to the circuit traces on the board, and a connector at the end of the cable plugs into the receptacle. The connector itself commonly contains signal conversion circuitry and is therefore referred to as a “transceiver.”
The mechanical and electrical characteristics of various SFP modules have been defined by industry organizations. For example, the SFP+ specification defines hot-pluggable modules that may be used at data rates up to 10 Gb/s. Details of these modules have been set forth by the SFF Committee in the SFF-8431 Specifications for Enhanced Small Form Factor Pluggable Module SFP+ (Revision 4.1, Jul. 6, 2009), which is incorporated herein by reference. This specification, as well as other SFP specifications, is available at ftp.seagate.com/sff.
Quad Small Form-factor Pluggable (QSFP) modules are used in similar applications to the SFP modules described above and support four parallel communication channels at 10 Gb/s. The mechanical and electrical characteristics of QSFP modules are described in the SFF-8436 Specification for QSFP+ Copper and Optical Modules (Revision 3.4, November, 2009), which is also incorporated herein by reference.
U.S. Pat. No. 7,335,033, whose disclosure is incorporated herein by reference, describes a form factor converter configured to concurrently connect to a circuit board module and a small form factor transceiver. The form factor converter includes an exterior portion defining a large form factor to fit within the device mounting section of the circuit board module, and an interior portion defining a small form factor location to receive at least a portion of a small form factor transceiver.
U.S. Pat. No. 7,934,959, whose disclosure is incorporated herein by reference, describes an adapter, which includes a mechanical frame, which is configured to be inserted into a four-channel SFP receptacle and to receive inside the frame a single-channel SFP cable connector. First electrical terminals, held by the mechanical frame, are configured to mate with respective first pins of the receptacle. Second electrical terminals, held within the mechanical frame, are configured to mate with respective second pins of the connector. Circuitry couples the first and second electrical terminals so as to enable communication between the connector and one channel of the receptacle while terminating the remaining channels of the receptacle.
10 GBASE-T Ethernet is a standard defined by IEEE 802.3an-2006, which is incorporated herein by reference. This standard provides connections at 10 Gb/s over unshielded or shielded twisted pair cables, over distances up to 100 meters. 10 GBASE-T can use the same cable infrastructure as legacy standards, such as 1000BASE-T, including Category 6 (or better) cabling and RJ45 connectors. It thus allows a gradual upgrade from 1000BASE-T using autonegotiation to select which speed to use. The features of 10 GBASE-T are described in detail by Barrass, et al., in a white paper entitled, “10 GBASE-T: 10 Gigabit Ethernet over Twisted-pair Copper,” published by the Ethernet Alliance (Austin, Tex., Version 1.0, August, 2007), which is available at www.teranetics.com/pdf/EA—10GBase-T-Overview.pdf and is incorporated herein by reference.